What are Radial and Axial Loads?

The permissible radial load is the upper limit value of the load that can be applied to the motor shaft. For example, if a radial load of 100 N is applied, the permissible radial load value has to be 100 N min.

I see. By the way, what happens if the load is larger than the permissible axial load or the permissible radial load?

The bearings inside the motor and gearheads may be damaged. Also, under radial loads, the shaft might bend or break.

I see! So that’s why we have to take care of the radial load. I'll look up the motor's permissible radial load in the catalog right away....Huh? Two values are listed for one motor. Is there any difference depending on the "distance from the end of the output shaft"?

See Figure 1. The permissible radial load has a different value depending on the point on the axis where the force is applied. The farther away the force is applied from the bearing, the stronger the force to bend the shaft becomes. That's why the permissible radial load becomes smaller the further away from the bearing.

I see. I understand now. By the way, the customer is using a belt conveyor mechanism, but they don't know how much radial load will be applied. How do I calculate?

The radial load can be calculated using the following formula.

Mmm... The formula is a bit complicated.

That's not the case. Look at Figure 2. It's easier to understand if you apply it to a conveyor.

Oh, that's true. With this I understand! But what do "K: load coefficient by drive method" and "f: service factor" mean?

Even though they are called conveyors, driving methods may be different such as flat belts or chains. It's necessary to take into account about the differences in drive method for radial load. That's the load coefficient depending on the drive method. As for the service factor, it can be driven 24 hours a day in the same direction, or it can be started and stopped frequently. You also have to consider those operation conditions.

It's quite deep isn’t it... I'll call the customer again, and ask for more details about the conditions.

I think that's a good idea. If the conditions are strict, we also have brushless motor BMU Series and BLE2 Series that have a high strength gearhead so please try to introduce them.

I understand. I'll introduce to the customer!

Oh, yes. If using a DC power supply, there's also a flange drive adapter that can be mounted on a parallel shaft gearhead to increase the permissible load. Can be used with DC input brushless motors (100 W only).

Installing on a parallel shaft gearhead means it can be retrofitted to the equipment that is already used.

Isn't it convenient? Another point is that unlike the gearhead, speed won't drop. Is it OK now?

Yes Thank you!